MPEG-21 is a multimedia specification that adds digital rights management capability to MPEG systems. MPEG-21 is an architecture that enables the searching, selecting, defining and managing the rights associated with digital media objects.

The MPEG-21 standard parts include digital item declaration (DID), digital item identification (DII), intellectual property management and protection (IPMP), rights expression language (REL), rights data dictionary (RDD) and digital item adaptation (DIA).

Part 2 defines the common set of terms and descriptions that can define a digital media object. Part 3 explains how digital item identification (DII) can uniquely identify any type or portion of content. Part 4 describes the intellectual property management and protection as a protocol that is used in the MPEG system to enable digital rights management (DRM).

Part 5 defines how rights expression language (REL) protocol can be used to specify rights to content along with fees or other consideration required to secure those rights. Part is contains the rights data dictionary (RDD).

Part 7 covers digital item adaptation (DIA) which defines the semantics and syntax that may be used to adapt the format or transmission of digital items. Part 8 provides reference software that can be used to demonstrate or test the operation of the MPEG-21 system. Part 9 describes file formats.